With the bend-straightening machine, the straightening is carried out in accordance with DE 34 45 544 A1, in which the workpiece, a pinion shaft or a camshaft for example, is deflected between two bases by a straightening die at the point at which an impact is present until a permanent change in shape occurs that is opposed to the impact and neutralizes it. The location of the impact is determined by rotating the workpiece through appropriate measuring devices in the longitudinal and circumferential directions. Either an individual straightening die is displaced in an appropriate fashion along the fixed workpiece in the longitudinal direction, or the workpiece is displaced in the longitudinal direction past a fixed straightening die, or there are several straightening dies present which are distributed over the length of the workpiece and which can be actuated as needed.
Usually, the workpiece is supported in a rotating fashion between center points that act as the workpiece seat. The straightening bases on which the workpiece is lying absorb the forces of the straightening die. In the case of a specific workpiece, a series of which are to be straightened, they remain at fixed locations when viewed in the longitudinal direction of the workpiece.
In general, the straightening die, which is attached to an upper part of the machine, is driven vertically by means of a hydraulic piston/cylinder unit. In the cases mentioned, the upper part of the machine is configured either as an upper crosspiece of a double-column press, or as an upper crosspiece of an open-front press with one C-shaped stanchion. In both cases, with the known bend-straightening machines of this type, it is necessary for a solid upper machine part to extend out over the workpiece to support the operating mechanism, or more specifically, the drive for the straightening die. For its part, this drive has a certain size, since the piston/cylinder unit has to have a specific cross-section because of the forces that arise, and therefore has to have a specific length because of the necessary length of the piston travel. In the case of U.S. Pat. No. 2,276,941, above the C-shaped stanchion a two-armed lever is supported, one arm of which acts upon a vertical spindle that carries the straightening die, and on the other arm of which a drive cylinder located behind the C-shaped stanchion acts.
In a different version, as is known from DE 26 06 061 A1 for example, the entire bend-straightening machine is rotated by 90.degree., so that the straightening force is exerted horizontally and the straightening bases and the straightening die are moved into a horizontal plane transversely to the longitudinal direction of the workpiece. With this type of bend-straightening machines as well, which usually exhibit a similar machine stanchion in the shape of a "C", the force that is acting upon the straightening die or dies is generated by means of one or more hydraulic piston/cylinder units at a part of the machine that is located to the side, and ahead of the workpiece, and that corresponds to the upper part of the machine in the upright version that was mentioned earlier.
The document SU-A1-1404 141 contains a hydraulic swiveling two-armed lever in which the straightening die is fastened to the free end of one of the arms and moves in the arc of a circle during straightening.
All known bend-straightening machines exhibit a considerable size as a result of the upper part of the machine or, ill the case of the horizontal of the horizontal version, the side part that corresponds to the upper part of the machine. The construction effort that is needed for the frame and the stand is increased even further as a result of the piston/cylinder units that form the single, straight-line hydraulic drive for the straightening die.